ABSTRACT
Considerable research has explored the relationship between intangible assets and firm performance in manufacturing and tertiary industries, but such studies remain scarce for the agri-food industry. In fact, numerous stresses, including the COVID-19 pandemic, have disrupted many activities along agri-food production chains in developing countries, resulting in huge pressure on sustainable agri-food production. Based on a sample of 94 A-share listed agri-food firms in China from 2008 to 2017, this study examines the impact of intangible assets on agri-food enterprises' productivity using generalized method of moments estimation. The results reveal differences between private and state-owned enterprises, indicating that the promotional productivity effect of intangible assets held by private agri-food enterprises was insignificant in the current period, but will be manifested three periods later, in contrast to state-owned enterprises. Due to the soft budget constraints and incentive mechanism of state-owned agri-food enterprises, intangible assets will not promote productivity. In addition, by pursuing the financialization profit model, agri-food enterprises will sacrifice productivity improvement, which can further lead to selective abandonment in the use of intangible assets. Simultaneously, there is a crowding-out effect between intangible and fixed assets in promoting agri-food enterprises' total factor productivity. The findings highlight the importance of the quality and conversion rate of intangible assets, particularly for agri-food enterprises, which are closely related to food security and stability. © 2022 Economic Society of Australia, Queensland
ABSTRACT
During the CIVID-19 pandemic, water samples were collected from 26 sampling points in 18 typical drinking water sources in Wuhan, located in the middle reaches of the Yangtze River. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) methods were used to measure the concentrations of 31 pharmaceuticals and personal care products (PPCPs) in the water samples. The pollution characteristics of PPCPs were analyzed and their ecological and health risks were assessed. The results showed that a total of 23 PPCPs were detected in the 26 sampling points. Among them, five types of PPCPs were detected with a detection rate of 100%, with total concentrations ranging from 102.44 ng•L -1 to 745.78 ng•L -1, and the average concentration was 206.87 ng•L -1. The highest concentrations were in salicylic acid (SA) and doxycycline (DIC), ranging from 28.24 to 534.24 ng•L -1 and 28.72 to 416.6 ng•L -1, respectively. According to the spatial distribution of PPCPs, the concentration of antibiotics in the Hanjiang River was higher than that in the Yangtze River, whereas the concentration of other types of PPCPs in the Yangtze River was higher than that in the Hanjiang River. The ecological risk assessment results showed that the toxic risk in algae was higher than those in invertebrates and fish. The risks of salicylic acid (SA), doxycycline (DIC), lincomycin (LIN), and chlortetracycline (CTE) to algae were at a high level, and the ecological risk of PPCPs in the Hanjiang River was generally higher than that in the Yangtze River. The health risk assessment results showed that the risk to adults and children by drinking water ranged from 1.14 × 10 -4 to 0.136 and from 1.04 × 10 -4 to 0.821, respectively. The health risk to children was higher than that to adults, although their levels were low. Compared with the concentrations of PPCPs in drinking water sources of Wuhan in recent years, under the CIVID-19 pandemic, the pollution status of PPCPs in the Yangtze River was at a medium level, whereas it was at a high level in the Hanjiang River. © 2022 Science Press. All rights reserved.
ABSTRACT
To address the issue of cross infection caused by elevator public buttons during COVID-19, a software algorithm based on machine vision for non-contact control of public buttons by gesture recognition is designed. In order to improve the accuracy of gesture recognition, an improved YOLOv4 algorithm is proposed. A Ghost module is designed based on attention mechanism, and the ResBlock module in YOLOv4 is improved to Ghost module. The experimental results show that, in the task of gesture recognition, the detection speed is improved by 14% and the detection accuracy is improved by 0.1% compared with the original model. The improved YOLOv4 algorithm is applied to the non-contact elevator buttons control system based on vision. The experimental results show that the detection accuracy reaches 98%, which meets the requirements of non-contact control for public elevators. © 2021, The Editorial Board of Journal of System Simulation. All right reserved.
ABSTRACT
OBJECTIVE: To evaluate systematically the efficacy and safety of COVID-19 vaccines. METHODS: PubMed, Embase, Cochrane Library, Clinicaltrial.gov, CNKI, Wanfang Data, China Biomedical Literature Service System, and China Clinical Trial Registry were searched for randomized controlled trials of COVID-19 vaccines published up to December 31, 2020. The Cochrane bias risk assessment tool was used to assess the quality of studies. A qualitative analysis was performed on the results of clinical trials. RESULTS: Thirteen randomized, blinded, controlled trials, which involved the safety and efficacy of 11 COVID-19 vaccines, were included. In 10 studies, the 28-day seroconversion rate of subjects exceeded 80%. In two 10 000-scale clinical trials, the vaccines were effective in 95% and 70.4% of the subjects, respectively. The seroconversion rate was lower than 60% in only one study. In six studies, the proportion of subjects who had an adverse reaction within 28 days after vaccination was lower than 30%. This proportion was 30%-50% in two studies and > 50% in the other two studies. Most of the adverse reactions were mild to moderate and resolved within 24 hours after vaccination. The most common local adverse reaction was pain or tenderness at the injection site, and the most common systemic adverse reaction was fatigue, fever, or bodily pain. The immune response and incidence of adverse reactions to the vaccines were positively correlated with the dose given to the subjects. The immune response to the vaccines was worse in the elderly than in the younger population. In 6 studies that compared single-dose and double-dose vaccination, 4 studies showed that double-dose vaccination produced a stronger immune response than single-dose vaccination. CONCLUSIONS: Most of the COVID-19 vaccines appear to be effective and safe. Double-dose vaccination is recommended. However, more research is needed to investigate the long-term efficacy and safety of the vaccines and the influence of dose, age, and production process on the protective efficacy.
ABSTRACT
A case of child SARS-CoV-2 infection with family cluster was reported in this paper. The boy's father was the first case in this family. Then the boy, the grandmother and the mother were infected one by one. Combined with literature analysis, it suggested that SARS-CoV-2 infection could be transmitted from person to person, and it was highly contagious. However, the children's symptoms were mild and the prognosis was acceptable in general. © 2020, Editorial Board of Medical Journal of Wuhan University. All right reserved.